1.2 Elements, Isotopes & Relative Atomic Mass

Question 1

What is an element?

Answer 1

An element is a substance made up of only one type of atom, so where all the atoms of a substance have the same number of protons

Question 2

How many different elements are there?

Answer 2

There are 118 different elements

Question 3

What is an isotope?

Answer 3

Isotopes are different forms of the same element, which have the same number of protons but a different number of neutrons

Question 4

Carbon-12 and Carbon-13 are isotopes of carbon. How do they differ?

Answer 4

Carbon-12 has 6 neutrons
Carbon-13 has 7 neutrons

Question 5

What does relative atomic mass mean?

Answer 5

Relative atomic mass is the average mass of all the isotopes of an element, taking into account the abundance and mass number of each isotope

Question 6

What is the formula for relative atomic mass?

Answer 6

Sum of:
(isotope abundance * isotope mass number) / sum of abundance of all isotopes

Question 7

What is an element symbol?

Answer 7

An element symbol is a one or two letter abbreviation for a chemical elements name

Question 8

Isotopes are atoms with the same atomic number but different _____ numbers.

Answer 8

Mass

Question 9

Isotopes are atoms with the same number of ______ , but different numbers of ______ .

Answer 9

Protons, neutrons

Question 10

An atom has 13 protons and 14 neutrons. What is its mass number?

Answer 10

27

Question 11

An atom has 13 protons and 14 neutrons, What is its atomic number?

Answer 11

13

Question 12

Lithium naturally exists as two isotopes: lithium-6, with an abundance of 7.6%, and lithium-7, with an abundance of 92.4%
What is the relative atomic mass of lithium?

Answer 12

6.92

Question 13

Uranium-235 has 92 protons. How many neutrons does it have?

Answer 13

143